With the black plates of
grips, it’s Merwin & Bray, the other, with the brown plates it is Eagle Arms &
C°, the only difference is that the Eagle have a cylinder with 6 blows whereas
Merwin & Bray have only 5.

These cupfire shells were
developed to circumvent the Rolling White patent of S/W.

The shells are loaded from
the front of the cylinder and ejected by the rod mounted behind it.